1. Field of the Invention
The present invention generally relates to an information processing apparatus, an information processing method, and an information providing medium and, more particularly, to an information processing apparatus, an information processing method, and an information providing medium for allowing easy recognition of a positional relationship between a particular user and another.
2. Description of Related Art
A cyberspace service named Habitat (trademark) is known in the so-called personal computer communications services such as NIFTY-Serve (trademark) of Japan and CompuServe (trademark) of US in which a plurality of users connect their personal computers via modems and public telephone network to the host computers installed at the centers of the services to access them in predetermined protocols. Development of Habitat started in 1985 by Lucas Film of the US, operated by Quantum Link, one of US commercial networks, for about three years. Then, Habitat started its service in NIFTY-Serve as Fujitsu Habitat (trademark) in February 1990. In Habitat, users can send their alter egos called avatars (the incarnation of a god figuring in the Hindu mythology) into a virtual city called Populopolis drawn by two-dimensional graphics to have a chat (namely, a realtime conversation based on text entered and displayed) with each other. For further details of Habitat, refer to the Japanese translation of "Cyberspace: First Steps," Michael Benedikt, ed., 1991, MIT Press Cambridge, Mass., ISBN0-262-02327-X, the translation being published Mar. 20, 1994, by NTT Publishing, ISBN4-87188-265-9C0010, pp. 282-307.
The related art cyberspace system represented by above-mentioned Habitat operated in the above-mentioned personal communications services has a multi-user capability in which a plurality of users share the same virtual reality space displayed in two-dimensional graphics via the client terminals to share the movement and the like of avatars of these users.
However, the related art multi-user capability is restricted to only specified users, not open to unspecified users. Namely, taking the above-mentioned Habitat for example, users are required first to purchases dedicated personal computer communications software, install the software program in their own personal computers (the client terminals), connected the personal computers to the host computer via the modem and the public telephone network, and register themselves as members of Habitat by online sign-up. only after the registration, they can access the virtual reality space. Therefore, the virtual reality space is available only to the registered members, excluding the unspecified users.
Moreover, in the related art cyberspace system represented by Habitat, a virtual street, a virtual room interior, and the like are drawn in two-dimensional graphics. In such an environment, movement of an avatar backward or forward is realized simply by moving it up or down in a two-dimensional background, providing poor representation for enabling the user to experience walk or movement in the virtual space. Because this scheme makes the user look at the virtual space in which the user's avatar and another user's avatar are shown from the viewpoint of a third person, the sense of pseudo experience is marred to a large extent. Therefore, realization of the walk-through capability has been awaited by the industry concerned, in which the virtual space is displayed in three-dimensional graphics and a user can walk freely in the virtual space from the viewpoint of an avatar, thus enhancing the sense of pseudo experience.
On the other hand, for a related art example for realizing the sharing of a three-dimensional virtual reality space on a network, a system of FIG. 31 is known which is constituted by client terminals 3-1 through 3-3 interconnected by the LAN (Local Area Network) installed in companies or laboratories.
First, all client terminals 3-1 through 3-3 read graphics data that describe the same three-dimensional space to display the same three-dimensional space. At this point of time, the three-dimensional spaces visually recognized by all users match each other.
Meanwhile, if, at a client terminal 3-1, the user changed positions of his avatar A from the position indicated by a dashed line to the position indicated by a solid line as shown in FIG. 31 for example, information about the change (or change information) is sent from the client terminal 3-1 to client terminals 3-2 and 3-3 via a LAN, not shown. Then, based on the change information from the client terminal 3-1, display is changed at the client terminals 3-2 and 3-3.
Namely, as shown in FIG. 31, the change information about the positional change of avatar A at the client terminal 3-1 (in the example of FIG. 31, "Move Object to (10,20,30)") is sent to the client terminals 3-2 and 3-3, at which display of avatar A is changed from the position indicated by dashed line to the position indicated by solid line according to the change information. Thus, avatar A moved at the client terminal 3-1 is also moved at the client terminals 3-2 and 3-3.
Likewise, if a change is made to the virtual reality space at the client terminal 3-2 or 3-3 other than the client terminal 3-1, the change is reflected at the other client terminals, thus allowing the users of all client terminals to share the same virtual reality space.
It should be noted that an object representing an avatar, or an later ego of a user, can be moved in the virtual reality space, entered in it, and made exit from it; in other words, the avatar is changed in its states or the states are updated. So, such an object is appropriately called an update object hereinafter. On the other hand, an object representative of a building constituting a town in the virtual reality space is used commonly by a plurality of users and does not change in its basic state. Even if the building object changes, it changes autonomously, namely it changes independent of the operations made at client terminals. Such an object commonly used by a plurality of users is appropriately called a basic object hereinafter.
Meanwhile, FIG. 32 shows an example of display of Cyber Gate (trademark), a VRML browser having a multi-user capability developed by Black Sun Interactive of US. A shared virtual reality space is displayed in a main window open on the left side of the figure.
In this case, if an avatar is displayed in the main window, the user can recognize that another user exists in the same virtual reality space. However, if another user existing in the same virtual reality space is not near the user or, even if another user is near the user, if another user is behind the user or hidden behind some object, the user cannot recognize the existence of another user. If this happens, the user must walk about in the virtual reality space, looking about another user.
To meet such a requirement, viewers such as mentioned above generally have a so-called radar capability.
In Cyber Gate, a VRML browser, shown in FIG. 32, performing a predetermined operation opens a radar window shown on the right side of the figure, in which a two-dimensional image indicating a top view of the virtual reality space is displayed.
Hence, by looking at this radar window, the user can recognize the position of another user and move to him while looking at the display.
In the related art technology, however, as shown in FIG. 32, the two-dimensional image showing the position of another user is shown in the radar window open at a position different from that of the main window in which the virtual reality space is shown.
Consequently, the user must move his line of sight from the main window to the radar window, check the position of another user, return the sight line again to the main window, and perform a predetermined operation such as movement, resulting in complicated and cumbersome operations.